1. Field of the Invention
The present invention relates to techniques for viewing three-dimensional data and, more particularly, to a method and apparatus for viewing data for a structure which has been tracked through three-dimensional data.
2. Description of the Related Art
In using three-dimensional data, images of many structures do not remain in a given two-dimensional plane. As a result, when viewing three-dimensional data on a conventional computer screen, it is difficult to identify and trace these non-planar structures within the three-dimensional data.
Tracking approaches are known, but these known tracking approaches operate only on two-dimensional data. See, Hoffmann et al., Automated Tracking and Computer Reproduction of Vessels in DSA Images, Investigative Radiology, vol. 25, pp. 1069-75, October, 1990; and Chaudhuri et al., Detection of Blood Vessels in Retinal Images Using Two-Dimensional Matched Filters, IEEE Transactions on Medical Imaging, Vol. 8, No. 3, pp. 263-269, September 1989. Even assuming the known tracking approaches track the structure correctly in two-dimensional data, the images produced from two-dimensional data are inferior to those images that would be produced by three-dimensional data.
In any case, once a structure is tracked, it must be displayed for a user. Conventionally, a tracked structure could at best be merely hightlighted in the original dataset. In order to visualize the structure, the user would have to manually search through the three-dimensional data until the structure was found and then, in order to follow the structure throughout the data, the user would have to make manual adjustments to change to different planar data slices. The conventional display methods make it difficult for a user to extract or interpret the data concerning the tracked structure. The conventional methods also make no effort to minimize the amount of data displayed which does not pertain to the tracked structure.
Three-dimensional data offers significantly more information to a user than does two-dimensional data. This additional dimension makes the images eventually displayed more meaningful to the user. One type of three-dimensional data is magnetic resonance imaging (MRI) data which is used by doctors for diagnosis of patients. MRI data is becoming useful in the diagnosis and treatment of blockages existing in a patient's coronary arteries.
Consider for example the problem of tracking or viewing arteries. Currently, a medical doctor's diagnosis is made by viewing only a single (two-dimensional) slice of MRI data at a time. Although the particular slice of data is accurate, it is difficult for the doctor to accurately evaluate the health of the coronary arteries because only discrete slices of data can be viewed one at a time. Although a doctor can switch back and forth between slices in an attempt to follow an artery, such data is confusing and difficult to interpret because there is no information as to what happens to the artery between such data slices. Also, due to the interplay of various images, locating the artery being evaluated in each slice of data is difficult. Hence, the doctor's diagnosis is hindered because three-dimensional tracking is unavailable to assist the doctor by identifying and/or extracting the relevant data concerning the structure being tracked.
Thus, since known methods for displaying tracked structures are inadequate, there is a need for a technique to visualize structures, such as arteries, which have been tracked through three-dimensional data so that the artery or other tracked structure can be easily and readily viewed.